1. Field of the Invention
The present invention is directed in general to the field of semiconductor devices. In one aspect, the present invention relates to packaging of semiconductor devices in a planar panel configuration to provide shielding against electromagnetic interference.
2. Description of the Related Art
Semiconductor and other types of electronic devices are often encapsulated wholly or partly in plastic resin to provide environmental protection and facilitate external connection to the devices. Such devices also need to be protected from electromagnetic interference (EMI) which is the undesired electrical signals, or noise, in electronic system circuitry caused by the unintentional coupling of electromagnetic field energy from other circuitry, such as wires, printed circuit board conductors, connector elements, connector pins, cables, and the like. For example, multiple chip modules (MCM) are semiconductor devices having a plurality of discrete microelectronic devices (e.g., a processor unit, memory unit, related logic units, resistors, capacitors, inductors, and the like) that are connected together on a single MCM substrate. Conventional approaches for shielding against EMI have used board or system level EMI shielding techniques, though this does not provide protection against interference caused by modules within the board or system. Other shielding techniques have attempted to protect against radio/electromagnetic interference by using conformal shielding technologies to packaging the individual circuit modules (e.g., MCMs), such as by using wire bond grounding connection techniques, laser-drilled via grounding connection techniques, or double-cutting methods. An example of this approach is with mobile phone designs which seek to push EMI shielding from metal lids on phone boards to the discrete packaged RF module level. However, these techniques require extra substrate space to apply the shielding, or impose an extra space and double saw operation, or otherwise increase the cost and complexity of the packaging process. In addition, these techniques typically require post mold assembly processes to add conformal EMI shielding to the packaged circuit modules, such as by drilling blind vias in the package molding compound which are then filled with a conductive material to form a shielding via in the molding compound. However, there are a number of alignment problems with forming blind vias that can impact device reliability and yield, such as creating electrical shorts to signal pads and/or signal paths or connection failures from mis-alignment.
Accordingly, there exists a need for a packaging scheme that provides improved EMI shielding. There is also a need for an improved process for integrating shielding structures in packaged circuit modules. In addition, there is a need for a reliable and cost effective semiconductor device package that provides reliable EMI shielding with little or no impact on the size of the packaging device. There is also a need for improved packaging processes and devices to overcome the problems in the art, such as outlined above. Further limitations and disadvantages of conventional processes and technologies will become apparent to one of skill in the art after reviewing the remainder of the present application with reference to the drawings and detailed description which follow.
It will be appreciated that for simplicity and clarity of illustration, elements illustrated in the drawings have not necessarily been drawn to scale. For example, the dimensions of some of the elements are exaggerated relative to other elements for purposes of promoting and improving clarity and understanding. Further, where considered appropriate, reference numerals have been repeated among the drawings to represent corresponding or analogous elements.